Wow - According to their projections based on current usage, I'm seeing a 100x increase in my daily cost. I guess I will be migrating off of App Engine. I'm feeling pretty burned at this point.
some apps get high multiples because they're using resources that weren't counted before, or were counted differently; that's why we enabled side-by-side billing now (before we switch on billing). if you email me your appid (psm@google.com) we can help. you should also review the FAQ and the tuning tips web page that we put together.